Maternal and neonatal benefits of induction of labor

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According to a recent study published in JAMA Network Open, induction of labor at 39 weeks improves maternal labor-related and neonatal outcomes.

In cases where the maternal and neonatal risks of continued pregnancies are worse than those of induction of labor, such as in post partum pregnancies past 41 weeks, cases of suspected poor fetal growth, or medical issues such as hypertension or prelabor rupture of membranes, induction of labor may be recommended.

Elective induction of labor is induction without medical indication and has been discouraged because of associated risks of adverse birth outcomes and cesarean delivery. However, while these risks are increased in elective induction of labor compared to spontaneous labor, not undergoing elective induction will not always lead to spontaneous labor in pregnant individuals.

An increase in elective induction at term has been observed worldwide, along with associated reduced incidence of cesarean birth. Differences in outcomes for children born after 39 weeks through induction of labor compared to expectantly managed birth have not been reported.

While neonatal-related outcomes for induction of labor at 39 weeks have been studied, maternal labor-related outcomes have not been determined. To identify how induction of labor at 39 weeks impacts maternal outcomes, investigators conducted a systematic review and meta-analysis.

Primary search terms were related to labor, induction of labor, and perinatal outcomes. Databases consulted included MEDLINE, Embase, Cochrane Central Library, World Health Organization, and ClinicalTrials.gov. Studies from database inception to December 8, 2022, were examined.

Included studies were randomized clinical trials, cohort studies, and cross-sectional studies about the association between elective induction at 39 weeks and neonatal outcomes. These studies also made comparisons between individuals with elective induction at 39 weeks and those with expectant management.

Exclusion criteria included having individuals with medical indications for induction of labor in the induction group, having unclear gestational age parameters, and only assessing multiple pregnancies. If multiple studies shared a population, the study with the larger cohort was included.

Study screening and data extraction was performed using Covidence systematic review software. After removing duplicates, texts were independently examined by 2 reviewers, with a third reviewer consulted during discrepancies. 

Data extracted included year of publication, author, country of study, study design, study population, parity, maternal outcomes, and neonatal outcomes. Bias assessment was performed independently by 2 reviewers using the Newcastle-Ottawa Scale and Cochrane Risk of Bias 2 tool.

There were 14 studies in the final analysis, including 12 retrospective cohort studies, 1 cross-sectional study, and 1 randomized clinical trial. In total, there were 86,555 women who underwent induction of labor at 39 weeks’ gestation throughout the studies.

Common maternal outcomes reported include third- or fourth-degree perineal injury, operative vaginal birth, post partum hemorrhage, and emergency cesarean section. Common neonatal outcomes included shoulder dystocia, macrosomia, low 5-minute Apgar score, and neonatal intensive care unit (NICU) admission.

The risk of third- or fourth-degree perineal injury was reduced by 37% through induction of labor at 39 weeks. A significant reduction of operative vaginal birth risk was also found through induction of labor, along with minor reductions in post partum hemorrhage and emergency cesarean section.

Neonatal outcomes also saw reduced risks from induction of labor at 39 weeks, including a 34% reduction in macrosomia risk and a 38% reduction in low 5-minute Apgar score risk. Shoulder dystocia and NICU admission risks did not differ between study groups.

Risks of third- or fourth-degree perineal injury and macrosomia were only reduced from induction of labor in multiparous women, while risks of NICU admission were only reduced from induction in nulliparous women. Emergency cesarean delivery saw reduced risks in both multiparous and nulliparous women.

Shoulder dystocia saw increased risks in nulliparous women, indicating a need to discuss risks with nulliparous women before performing induction of labor. Overall, a low risk of bias was found among the studies.

These results indicated benefits for induction of labor at 39 weeks’ gestation. Investigators recommended discussing risks with nulliparous women to improve safety.

Reference

Hong J, Atkinson J, Roddy Mitchell A, et al. Comparison of maternal labor-related complications and neonatal outcomes following elective induction of labor at 39 weeks of gestation vs expectant management: A systematic review and meta-analysis. JAMA Netw Open. 2023;6(5):e2313162. doi:10.1001/jamanetworkopen.2023.13162